In recent years, hydraulic excavators and other construction machines that incorporate a wireless communication apparatus to exchange signals with the outside and perform various processes are becoming widespread. The relevant technologies are disclosed, for instance, by Patent Documents 1 and 2. The technology described in Patent Document 1 is used to exchange work instruction data and work result data, which includes position data, between a wireless communication apparatus for each work machine and a management computer and provide management support for land surface treatment work, which includes a plurality of processes performed by using a plurality of work machines.
The technology described in Patent Document 2 is used to transmit component operation data from a hydraulic excavator operated at a work site to a base station computer and let the base station computer accumulate and calculate the component operation data and predict and manage the timing of parts repairs and replacements.
Meanwhile, the wireless communication apparatus generally includes a communication device, an antenna, and an antenna cable, and the communication device is connected to the antenna with the antenna cable. A conventional technology for detecting a break in the antenna cable is described in Patent Document 3. The technology described in Patent Document 3 uses an antenna cable that is integral with a detection cable having a shorter fatigue life than the antenna cable, and detects a break in the detection cable to predict the timing of antenna cable replacement.
A common technology for antenna cable break detection uses a signal wire that is laid along an antenna cable, and allows a detection current to flow in the signal wire. When it is detected that the detection current is shut off by a break in the signal wire, this technology concludes that the antenna cable is broken.    Patent Document 1: JP-A-2005-344482    Patent Document 2: WO 01/73217A1    Patent Document 3: JP-A-2002-56726